Manually adjustable choke valve



P 1952 c. s. WEYANDT ET AL 2,609,173

MANUALLY ADJUSTABLE CHOKE VALVE Filed Au 5, 1946 Ill INVENTOR. Ma C/I/PL 5. Maw/v01- 42 BY MW/LLE C/V /KFLV/ m @a waw FEW Arum 1.7

Patented Sept. 2, 1952 5 MANUALLY ADJUSTABLE CHOKE ALVE Carl S. Weyandt, Homer City, and Neville C. McKelvy, Blairsville, Pa... assignors to Syntron Company, Homer City, Pa., a corporation of Delaware This invention relates generally to improveinents in carburetors and more particularly to improvements in choke valves on carburetor for internal combustion percussionhand tools such as gasoline hammers, I

Percussion hand tools are employed for breakbig rock, concrete, cutting asphalt, drilling, digging or spading shale or clay, and for tamping, Fd-liVm round rods or sheathing and other similarwork. A percussion hand tool is a self-contained-machine that does not rely on a central power system or plant as do the electric or pneui s'i a d 1 15- -An internal combustion percussion hand tool is=yacomplete combustion engine comprising a cylinder with a single combustion chamber having an-idling captive piston and a free percussive piston operating therein. The idling captive piston operates the magneto and-supplies cooling air. The free percussive piston provides the repeated blows on the tool bit'to produce useful work. This hand tool is provided with a fuel tank for supplying the-carburetor and has a handle at-the top withiwhich to manipulate it while operating. I-I owever this-hand tool-has limitations as to the angle in which it may be used owing to the fact that it is supplied with fuel by means of a carburetor. By mounting the carburetor with the axis of the bowl at an angle to the axis of the cylinder this hand tool may be operated when disposed in a horizontal position.

The violent vibrations created by the free percussive piston and the relatively large combustion chamber produce many problems not ordinarily encountered with internal combustion engines and this invention is directed to improvements in carburetor choke valves for this percussion tool.

Another object is the provision of a manually operated latch for retaining the choke valve in its open position to prevent accidental closure due to vibration.

Other objects and advantages appear hereinafter in the following description and claim.

A practical embodiment illustrating the principles of this invention is shown in the accompanying drawings wherein:

tIgig. 1 is a view partially in section of the carbure r.

Fig. 2 is a top plan view of the carburetor shown in Fig. 1.

Fig. 3 is a sectional view taken on the line 33 of Fig. 2.

Fig. 4 is an enlarged detailed view partly in Application August s, 1946, Serial No. 688,186

1 Claim. (61 251- 11) 2 section showing the detent engaging thecam with the choke valve in another position than that illustrated in Fig. 1. f The carburetor shown in Figs. 1 to 4 is provided with the body member having a straight throat 5| which is enlarged at the inlet end as indicated at 52 for the purpose of receiving the choke valve 53'. The inlet and outlet mouths 54 and 55 of the throat 5i are flanged. The faces of these flanges are parallel with each other but their planes are disposed at an angle to the throat to permit the percussion tool to be horizontal position. 4

The underside of the carburetor body 50 is provided with an annular seat 55 toreceive the fuel bowl 51. An integral depending portion '58 extends from the underside of the body 50 to within the bowl and is provided with the-centrally disposed threaded hole for receiving the screw 6| which holds the bowl in place. The screw Bl has an axial and later-a1 pasageWay'BZ for connecting the inner. end of the threaded hole 60 to the interior of the bowl/ This passage in the bolt 6! permits the drillin of a straight bore 63 from the throat 5| through the body to the inner end of the hole 60. The outer e'n-d of the bore is provided with the idling jet nozzle '64. Thus the idling jet is straight, connecting a relatively large chamber, represented by the inner end of the hole 60, to the throat. It leans toward the outlet mouth and does not require piercing of the other side of the body as the drill may be inserted through the mouth 55 to form the bore 63. This provides a more eflicient and more compact carburetor unit as the idling Jet may be placed closer to the throttling valve 65 and the outlet mouth need only extend sufiiciently to allow clearance for the bowl seat 56. The bore of this idling jet is relatively large to provide a rich mixture of gasoline for idling because the combustion chamber is very large when the engine is started and permitted to idle. The sloping of the straight bore of the idling jet provides better flow of the fuel.

The shaft of the throttling valve 65 has a lever secured thereto for operating the same. The running jet 66 is formed by drilling a straight bore 6-! from the top of the body 50 through the venturi 68 in the throat ,5! and through the depending portion 58 to the bottom thereof. A nozzle 10 is secured in the bore 61 and is arranged to hold the venturi 68 in position if it is a separate body as shown. However this venturi is preferably made as an integral part of the die cast body 50.

operated in -a to regulate the engine for better operating condi-n tions from day to day, depending upon the atmospheric condition, but this adjustment is insufficient to prevent the engine from operating at either limit. This step also prevents the terrific vibration of the tool from changing the needle valve adjustment beyond the range of the shoulders thereon. However a forked extension rod may be inserted in the holesin the knob "I3 of Fig. 2 and extend upwardly to permit the operator to manually adjust the needle valve H while the. toolis operating.

-- Y The. shaft of the choke valve .53 as the integral cam member and lever 16 secured thereto.

The cam member has spaced'projections l1- and 18 between which are a series of seats arranged to be engaged by the ball of the detent 8.0 for holding the choke valve at any one of the positions represented by the seats. However the vibration of the percussion tool may cause this valve to move around even though a heavy spring is. employed in the detent. The spring latch BI is arranged to engage the cam projection 11 and thereby provide a positive latch for holding the choke valve in its open position. A finger pro- .iection 82, is secured to the latch 81 to permit the index finger to release the latch by raising it above the projection 11 while the thumb moves the lever and the valve in a counterclockwise direction to close the choke valve. Otherwise the latch 8| will maintain the choke valve in its open position as the vibrations of the tool are unable to deflect the spring latch 81 sufliciently to release the ehoke valve.

The fuel bowl is provided with the hinged float 8-3 arranged to actuate the gasoline inlet valve 4 84 that regulates the flow of fuel from a tank through the line 42. In cold weather the spring 4 latch 8| may be readily raised to partially close the choke valve and enrich the mixture to start the engine. After it has warmed up the choke valve is opened and the latch automatically drops back into place.

We claim:

A manuallyoperated choke valve 01: a. carburetor supplying; fuel to aninternalnombus'tion percussion hand tool, comprising a casing in which said choke valve is mounted, a cam fixed to move with the choke valve and having spaced projections with a'series of seats therebetween, a sprin loaded ball detent engaging said seats to hold said valve at different positions between its open 9 fil P0 1 19 1 and a e ble arm on said casing to engage one of said projections and lock the valve in its fully open position.

' CARL S. W'EYANDT.

NEVILLE C. McKELVY.

REFERENCES CITED I The followin reie n are o ecord in. the

file of this patent;

UNITED STATES Number Name Date 511,518' Field Dec. 26, 1893 750,322 Daley Feb. 2, 1904 'l, 5 84,'7'59 Eynon May 18,1926

1,674,029 Welch June 1-9, 1928 1,252,551 Ensign et al. Apr. 1, 1930 1 919 793 Linga July 25,1933 1,921,736 Erade Aug. 9; 1933 1, 8 ,75 P e n. C.- 4 1934 $0 5 5 Hu t -e--..---=.-- Oct. 1, 1 2 ,191,039 Baker Dec. '7, 1937 2,156,128 Shall e Apr. 25; 1939 2,341,685 Bicknell et a1. Feb. 1 5, 1944 2,994,665 Christian Feb. 12, 194 6 2, 33,007 -Weyandt Dec. 21.3, 1 .47

FOREIGN PATENTS Number Country Date 243,847 Great Britain Dec. 10, 1925 507, 4=7 i Great Britain June 16, 1939 Fi-ance Dec. 28, "19 25 

